Gab Kovacs1 and Paula Briggs2
(1)
Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
(2)
Sexual and Reproductive Health, Southport and Ormskirk Hospital, Southport, UK
Breech, Transverse & Unstable Lie, Brow, Face & Compound Presentation
Definition
Incidence
Aetilogy and Pathogenesis
Clinical Assessment
Treatment
Complications
Prognosis
Breech, Transverse & Unstable Lie, Brow, Face & Compound Presentation
Definition
Any presentation that is not a longitudinal lie with a vertex presentation is said to be a malpresentation.
A Breech presentation is when the baby’s feet or buttocks are presenting in the pelvis.
A transverse/oblique lie is when the head is not in the pelvis and the fetus is in a horizontal position.
An unstable lie is when the presenting part changes position.
A brow presentation is when the head is deflexed and instead of the vertex, the brow presents.
A compound presentation is when there is a head or a breech plus a limb presenting.
Incidence
Although one in five fetuses are a breech presentation at 28–32 weeks, by term most turn to a cephalic presentation, with only one in 25 persisting a breech presentation. Transverse and unstable lie are uncommon. Brow and compound presentations are only diagnosed in labour, and are vey uncommon.
Aetilogy and Pathogenesis
Most babies are in a cephalic presentation as the natural shape of the foetus matches the shape of the uterine cavity (Fig. 23.1). Any factor that changes this “best-fit” relationship can predispose to malpresentation.
Fig. 23.1
The shape of the foetus matching the shape of the uterus
To analyse possible causes one can use the “Passengers/passages/powers” framework.
Possible cause of malpresentation:
· Passengers
· Foetus – any abnormality of the foetus which alters its usual shape
§ Anencephaly
§ Hydrocephaly
§ Extended head (possibly due to a thyroid tumour)
§ Undiagnosed prematurity
· Liquor- polyhydramnios – giving the foetus a chance to move around
· Placenta – Placenta praevia (probably the most serious) – if the placenta occupies the lower uterus, the head will be unable to engage.
· Membranes – not a cause
· Cord – not a cause
· Passages
· Boney – severe restriction of pelvic inlet
· Soft tissue
§ Uterine abnormality eg septum
§ Lower segment or cervical fibroid deforming uterine cavity
· Powers
· Primary – Lax floppy grand-multigravid uterus
· Secondary – these cannot effect presentation
Clinical Assessment
History
The woman may describe kicking low down in her abdomen, or the feeling of a hard lump (the head) under the ribcage.
Examination
In a breech presentation, the head will not be palpable in the pelvis, and will be palpable in the upper abdomen.
In an unstable lie, the head will be detected in a different position at each examination or can be moved around the abdomen.
Compound and brow presentations will be diagnosed in labour only on vaginal examination.
Investigations
The most useful investigation is ultrasound, which can eliminate the causes listed above. A specialist obstetric ultrasound should be arranged when a malpresentation is suspected.
Treatment
Medical
The only antenatal treatment for a breech presentation is external cephalic version (ECV). Performing ECV decreases the chance of Caesarean Section being required. If a Caesarean Section is indicated for other reasons, an ECV should not be performed. Usually ECV has a low complication rate, but about 1 in 200 attempts require immediate Caesarian Section for an adverse outcome (abruption of the placenta, or acute foetal distress). It should only be attempted with a normal uterus and no foetal contraindications eg intrauterine growth restriction.
For transverse or unstable lie diagnosed during labour, the only options is Caesarian Section.
With brow presentation the foetal head sometimes flexes, allowing vaginal delivery, similarly for compound presentation, the limb may move during labour. Otherwise Caesarian Section is required.
Surgical
More than 90 % of breech presentations at term are now delivered by Caesarean Section. All other malpresentations need to be delivered by Caesarian Section if they persist at the onset of labour.
Complications
The risk of serious perinatal morbidity or mortality is about 5 % for a breech delivery.
Prognosis
In 2000, the “Term Breech Trial (TBT)” was published. This showed that both perinatal morbidity and mortality were significantly reduced by elective Caesarian Section. Since then most breech presentations have been delivered by Caesarian Section. There has been some criticism of the TBT methodology. Consequently a “trial of vaginal delivery” can be considered by an experienced obstetrician, subject to certain conditions. This requires appropriate infrastructure, especially the ability to perform immediate Caesarian Section.
Contraindications to trial of vaginal delivery
· Clinically inadequate maternal pelvis
· Any other obstetric complication eg hypertension
· Any foetal abnormality incompatible with vaginal delivery eg extended head
· Foetal growth restriction or macrosomia
Prerequisites for a trial of vaginal delivery
· Continuous foetal heart rate monitoring
· Ability to perform Caesarian Section without delay
· Immediate availability of an experienced obstetrician
· Appropriate counselling of the couple
Principles of breech delivery
· Any sign of foetal distress or delayed progress should be an indication for a Caesarian Section
· Appropriate analgesia should be provided to allow manipulation of the baby
· At full dilatation, when the perineum is distended an episiotomy should be performed and the woman encouraged to push until the legs and buttocks have been delivered
· Cover the breech with a warm nappy “breech cloth” and bring down a loop of umbilical cord
· Deliver the shoulders by repeated lateral rotation till the arms drop
· Once the shoulders are delivered let the body hang to allow the head to descend into the pelvis
· Once the hairs at the nape of the neck are visible, swing the body (wrapped in the breech cloth) over the pubis onto the abdomen. This extends the head and should bring the face onto the perineum.
· When the face is visible, suck out the nose and mouth
· Deliver the “after coming” head by forceps
· Manage the third stage as usual